1. Field of the Invention
This invention relates to semiconductor imaging devices and more particularly to imaging devices and systems suitable for infrared qualitative detection.
2. Decription of the Prior Art
A typical prior art infrared imaging system has includes the following components: scanning optics including mirrors for moving incident lines of infrared radiation from the target or object; an array of infrared detectors suitably maintained in a cooled condition; a plurality of voltage amplifiers connected to each detector in the array; the electro-optic multiplexer including a suitable array of light emitting diodes, the scanning optics being synchronized with the target optics; a vidicon for receiving the outputs from the electro-optic multiplexer and suitable for driving a conventional CRT display.
Charge transfer devices, including charge-coupled devices and bucket-brigade devices, have been successfully employed in solid state visual imaging systems. An example is described by Weimer, Kovac, Shallcross and Pike in "Self-Scanned Image Sensors Based on Charge Transfer by the Bucket-Brigade Method," I.E.E.E. Transactions on Electron Devices, November 1971, which is incorporated herein by reference. Such systems eliminate much of the scanning, amplifying and multiplexing components of the conventional imaging systems. However, it has not been heretofore possible to make wide spread application of such simplified visual imaging systems to IR imaging because of certain problems unique to IR imaging. The primary problems have been one of fabrication of IR sensitive devices and the suppression of interfering background without using unduly complex electronics.
It is therefore a feature of this invention to provide an improved means of fabricating charge transfer devices to increase their sensitivity to infrared radiation.
It is another feature of this invention to provide an improved charge transfer device sensitive to infrared radiation applicable in a conventional charge-coupled or bucket-brigade visual imaging system without additional complex electronics.
It is yet another feature of this invention to provide an improved charge transfer device suitable for infrared radiation detection by modifying only slightly charge transfer devices that have been proven with respect to visual imaging application.